Axial setting device

ABSTRACT

An axial setting device in a housing, especially for actuating a multi-plate coupling whose friction plates are alternately connected in a rotationally fast and axially displaceable way to the one and the other respectively of two parts rotatable relative to one another, which rest against an axially fixed supporting disc and which can be loaded by an axially displaceable pressure disc, comprising a setting disc which is rotatably supported in the housing, which is mounted so as to be axially fixed in the housing and which is rotatingly drivable, a pressure disc which is held in the housing, which is held in a rotationally fast way by anti-rotation means arranged in the housing and which is axially displaceable in the housing, ball groove configurations in the surfaces of the setting disc and of the pressure disc, which surfaces face one another, which ball groove configurations extend in the circumferential direction, have oppositely directed gradients across the circumference and are associated with one another in pairs, so as to jointly accommodate a ball, and rotary driving means for the setting disc mounted in the housing, wherein the anti-rotation means are designed so as to be releasable from the pressure disc.

BACKGROUND OF THE INVENTION

The invention relates to an axial setting device in a housing,especially for actuating a multi-plate coupling whose friction platesare alternately connected in a rotationally fast and axiallydisplaceable way to the one and the other respectively of two partsrotatable relative to one another, which rest against an axially fixedsupporting disc and which can be loaded in one embodiment by an axiallydisplaceable pressure disc, comprising a setting disc which is rotatablysupported in the housing, which is mounted so as to be axially supportedin the housing, which is mounted so as to be axially fixed in thehousing and which is rotatingly drivable, a pressure disc which is heldin the housing, which is held in a rotationally fast way byanti-rotation means arranged in the housing and which is axiallydisplaceable in the housing, or which can be loaded—in anotherembodiment—by an axially displaceable setting disc, comprising a settingdisc which is rotatably supported in the housing, which is mounted so asto be axially displaceable in the housing and which is rotatinglydrivable, a pressure disc which is held in the housing, which is held ina rotationally fast way by anti-rotation means arranged in the housingand which is axially fixed in the housing, ball groove configurations inthe surfaces of the setting disc and of the pressure disc, whichsurfaces face one another, which ball groove configurations extends inthe circumferential direction, have oppositely directed gradients andare associated with one another in pairs, so as to jointly accommodate aball and rotary driving means for the setting disc mounted in thehousing.

Setting devices of said type combined with the above-mentionedmulti-plate coupling are known in different designs and for differentapplications.

DE 38 15 225 C2 describes such a device which is integrated into a bevelgear differential drive. The setting disc is directly driven by aconical pinion which engages a bevel gear toothing at the setting disc.

From DE 40 07 506 C1, there is known a device of said type which is usedin a manual gearbox. The driving means for the setting disc comprise thesame parts as mentioned above, but in addition, they comprise a spurgear reduction drive.

DE 41 06 503 C1 refers to a further development of the latterapplication. It shows the anti-rotation means for the pressure discwhich consist of a tongue-and-groove assembly, with the tongue beingconnected to the fixed part of the housing and the groove constitutingan individual notch at the pressure disc.

EP 0 368 140 B1 describes different applications for setting devices ofsaid type, and inter alia, it can be seen that at its circumference, thesetting disc can comprise a worm toothing or helical toothing andsetting can be effected by means of a worm driven by a motor andpositioned on the motor shaft.

In the case of the devises mentioned first, the driving motor for thesetting disc has to be kept under voltage for as long as a positivesetting force is to be maintained. This means that the capacity of themotor has to be higher or that the motor requires an additional brakingdevice. The latter device can only be equipped with non-self-inhibitingrotary drive means because the device has to feature as little frictionas possible. Irrespective of the latter, in the case of failureinvolving a voltage brake-down, a reverse motion of the device effectedby returning forces is almost impossible due to the high friction in therotary drive means provided in the form of a worm drive. In a case offailure involving voltage brake-down, a multi-plate coupling closed byrotating the setting disc relative to the pressure disc would bereleased by the rotary drive means only hesitatingly.

SUMMARY OF THE INVENTION

It is the object of the present invention to improve a device of thelatter type in that a rapid return from an assumed set position of thedevice can be effected by simple means in the sense of reducing thesetting path. The objective is achieved in that anti-rotation means aredesigned so as to be releasable from the pressure disc.

The conventional mode of operation is such that, normally, the settingpath of the axial setting device is increased or reduced by actuatingthe rotary drive means which act on the rotatingly drivable setting discwhich, via the balls, acts on/is supported on the pressure disc held ina rotationally fast way, with the oppositely directed gradientsdetermining the setting path as a result of the relative rotation of thesetting disc relative to the pressure disc. In addition, the specialmode of operation in accordance with the invention consists in that, inthe case of failure or for special operating conditions, a rapidreduction of the setting path is effected independently of an actuationof the rotary drive means in that the pressure disc is released forrotation purposes so that the counter forces acting on the pressuredisc/setting disc act as returning forces which are reduced because thepressure disc is able to rotate freely relative to the setting discwhich is held by the rotary drive means in a rotationally fast way or isdriven only slowly thereby, with the direction of rotation beingdetermined so as to be opposite to the direction of the oppositelydirected gradients of the ball groove configurations. As a result, thesetting path of the setting device is very quickly reveredautomatically.

Releasing the anti-rotation means can constitute a safety measure andcan be effected in a case of failure, for instance when there occurs avoltage brake-down. However, it is also possible to provide embodimentswherein the anti-rotation means can be released from the pressure discfor certain operating conditions and can, optionally, also be controlledpositively.

In a preferred embodiment, the anti-rotation means can be designed insuch a way that they comprise an axially displaceable pin which isaligned relative to the pressure disc, which, in a first position, canengage notches in the circumference of the pressure disc and which, in asecond position, is able to move radially out of the notches. The pinmust be able to slide in the notches in the direction of displacement ofthe pressure disc. In particular, the anti-rotation means can comprisean electromagnet which acts on the pin in its holding position, and saidholding position can be spring-supported. According to a particularlyadvantageous embodiment it is proposed that, at the circumference of thepressure disc, the free end of the pin and the flanks of the notchesform angles with the radial line which are greater than theself-inhibition angle, so that if the electromagnet is de-energised,with returning forces acting on the pressure disc/setting disc, the pinis suppressed automatically out of his position of engagement in one ofthe notches. To generate such returning forces, it is proposed inparticular that a pretension pressure spring, especially a plate spring,axially acts on the pressure disc towards the setting disc/on thesetting disc towards the pressure disc.

It is possible for the anti-rotation means to have any other design; inparticular, the form-fitting engagement can be replaced by afriction-locking engagement, i.e. it is possible to provide any type ofbraking device. In addition, the anti-rotation means, instead of beingset electromagnetically, can also be set hydraulically, pneumatically orin any other way.

As far as the design of the rotary drive means are concerned, it isproposed according to a preferred embodiment that, at the outercircumference of the setting disc, there is provided a worm toothing orhelical toothing and that there is provided a setting motor on whoseshaft, there is positioned a worm which engages the worm toothing orhelical toothing. In particular, it is proposed that the worm driveconsisting of the setting disc and the worm is self-inhibiting.

Because of the large transmission ratios of worm drives, the drivingforces to be proved by the setting motor are low. There is no need for areduction gear. To be able to stop the setting disc while it is in arotating position when the setting motor is de-energized, the worm gearis designed so as to be self-inhibiting.

In another embodiment there is provided that at the outer circumferenceof the setting disc there is provided spur gear toothing and there isprovided a setting motor on which shaft there is positioned a spur gearpinion.

A return motion of the setting device as a result of returning forcesacting on the pressure disc/setting disc cannot take place.Nevertheless, each position as set can be released without delay bydisconnecting the anti-rotation means from the pressure disc. The ballgroove configurations between the setting disc and the pressure disccause the pressure disc to be turned back in the sense of the pressuredisc approaching the setting disc/the setting disc approaching thepressure disc.

There is thus provided a setting device wherein, due to a hightransmission ratio in the worm device, the setting process can beeffected by low driving forces, and because of the self-inhibitingnature of the worm drive, a set rotational position of the setting disccan be maintained permanently when the setting motor is de-energised.Finally, the pressure disc is able to return freely from any positiveposition as set, in spite of the setting disc being in a fixed position.

It is also possible to use other drive concepts for the rotary drive ofthe setting disc, such as crown gear drives, spur gear drives, chaindrives, belt drives, cog belt drives, etc. In an embodiment, wherein hesetting device is driven by a spur gear drive, the driven setting discis able to return freely by axial motion in the gears ins spite of thesetting disc being held rotationally fixed by the drive.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are diagrammatically illustratedin the drawing wherein

FIG. 1 shows an inventive setting assembly in the form of a detail,

(a) in an axial view of the pressure disc,

(b) in an axial section.

FIG. 2 shows a setting assembly in accordance with the invention

(a) in connection with a friction coupling in a longitudinal sectionthrough the housing,

(b) in another embodiment in axial section.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 does not show the shaft on which the assembly is supported in thehousing, but it shows the bearing means for the shaft. FIGS. 1a and 1 bwill be described jointly.

FIG. 1 shows a setting disc 11 with a radial bearing 12 for supportingthe setting disc 11 on said shaft (not illustrated) and an axial bearing13 for providing axial support relative to the shaft. The setting disc11 comprises an outer helical toothing or worm toothing 14 engaging arotatingly drivable worm 15. By means of said worm 15, the setting disc11 can be rotated by a small angular amount relative to the housing 30in which the shaft (not illustrated) and the worm 15 are supported. At ashort axial distance from the setting disc 11, there is positioned apressure disc 17 in the housing 30, which pressure disc 17 rests axiallyagainst an axial bearing 18 by means of which it is able to act on amulti-plate coupling. A further pressure disc can be arranged betweenthe multi-plate coupling and the axial bearing 18. The outercircumference of the pressure disc 17 is provided with notches 19 whichcan be engaged by anti-rotation means firmly connected to the housing30.

In the end face 21 of the setting disc 11 and in the end face 27 of thepressure disc 17—said end faces facing one another—there are providedball groove configurations 22, 28 with oppositely directed gradients,which jointly accommodate a ball 23. At least two ball grooveconfigurations 22, 28 and ball 23 are distributed around thecircumference Said ball groove configurations support the pressure disc17 both radially and axially relative to the setting disc 11. In atleast one of the discs the ball groove configurations change the depthof same across the circumference of same, so that rotating the settingdisc 11 leads to an axial displacement of the pressure disc 17 to theextent that the latter is held by the anti-rotational means in thedirection of rotation.

The worm 15 is positioned on the shaft 24 of an electric motor 25 whichis firmly arranged in the housing 30. The worm drive 14, 15 isself-inhibiting so that, when the electric motor 25 is de-energized, therotational position of the setting disc 11 is secured. The unlockableanti-rotation means are formed by a pin 20 which is aligned radiallyrelative to the shaft axis and which, by means of an electromagnet 26,is held in the position of engagement in one of the notches 19. Theelectromagnet 26 is also firmly arranged in the housing 30. When theelectromagnet 26 is de-energized, the pin 20 can be pushed radiallyoutwardly into the released position by a pressure springs which freesthe pin and enables same to engage in on of the notches 19. As a result,the pressure disc 17 becomes freely rotatable and, under the returninfluence of axial forces coming from the multi-plate coupling and bymeans of the ball groove configurations 22, 28 and the balls 23, thepressure disc 17 is able to return into a rotational position in whichit is made to axially approach the setting disc 11, as a result of whichthe setting path of the device is clearly reduced. At its front end, thepin 20 is conical or, if it is rotationally secured, it is wedge-shapedand cooperates with the flanks of the notch 19. The flanks of the notch19 form an angle relative to the radial line which is large enough toprevent any self-inhibition between the pin and flanks to becomeeffective. As soon as, due to axial forces acting on the pressure disc17, rotational forces act on the pressure disc 17, the flanks push thepin automatically into its released position, thus permitting rapidrelease and safety switching, and the axial setting forces of thesetting device can be reduced rapidly and the setting distance can bereduced rapidly.

FIG. 2a) shows an inventive axial setting device cooperating with afriction coupling 31. The friction coupling is arranged in a housing 30and comprises a coupling carrier 33 which is supported in the housing 30by a shaft 34, and a shaft flange. For supporting purposes, there isprovided a rolling contact bearing 36. Furthermore, the couplingcomprises a shaft 37 which is supported directly in the shaft journal34. In this case, there is provided a needle bearing 38 for supportingpurposes. One part of the coupling plates is connected to the couplingcarrier 33 and another part of the coupling plates is connected to theshaft 37. At one end, the coupling plate package is delimited by asupporting disc 39 and at the other end by a pressure disc 41. Thepressure disc 41 is acted upon by a plate spring 40 which is supportedon the shaft 37 and applies returning forces to the setting device. Thesetting device can be seen to be provided with an axial bearing 18, thepressure disc 17 with notches 19, the setting disc 11, the radialbearing 12 and the further axial bearing 13, with the geometry of saidparts being only slightly modified as compared to the setting deviceaccording to FIG. 1. The axial bearing 13 is supported by a disc 42 onthe shaft 37. In this embodiment, the pressure disc 17 is rotationallysecured through the notches 19 against rotation relative to the housing30 by means which are not illustrated The setting disc 11 isrotationally driven via a reduction gear 43 by an electric motor 25. inthis embodiment, the axial adjustment of the pressure disc 11 in bothdirections of the setting path is effected entirely compulsorily by theelectric motor 25.

In FIG. 2b) a setting device different from that in FIG. 2a) comprises asetting disc 11′, which is rotatably drivable via straight gears 14′through a straight gear pinion 15′, and a pressure disc 17′ beingaxially supported on an axial bearing 13 and held against rotationrelative to the housing through notches 19′ by means 26′ which are notcompletely illustrated. These means are releasable from the notches sothat the pressure disc may freely rotate and the pressure disc 17′ mayreturn in axial movement without being driven by the straight gearpinion 15.

I claim:
 1. An axial setting device for actuating a multi-plate couplingwhose friction plates are alternately connected in a rotationally fastand axially displaceable way to the one and the other respectively oftwo parts rotatable relative to one another, which rest against anaxially fixed supporting disc and which can be loaded by an axiallydisplaceable pressure disc, comprising a housing, a setting discrotatably supported in said housing and mounted so as to be axiallyfixed and rotatingly drivable in said housing, said pressure discsupported in said housing in a rotationally fast way by anti-rotationmeans arranged in said housing and which is axially displaceable in saidhousing, ball groove configurations in the surfaces of said setting discand of said pressure disc, which surfaces face one another said ballgroove configurations extending in the circumferential direction andhaving oppositely directed gradients across the circumference and areassociated with one another in pairs, so as to jointly accommodate aball, and rotary driving means for said setting disc mounted in saidhousing, and wherein said anti-rotation means is designed so as to bereleasable from said pressure disc.
 2. An axial setting device accordingto claim 1, wherein said anti-rotation means comprise an axiallydisplaceable pin which is aligned radially relative to said pressuredisc, which, in a first position, can engage notches in thecircumference of said pressure disc and which, in a second position, isable to move radially out of said notches.
 3. An axial setting deviceaccording to claim 2, wherein said anti-rotation means comprises anelectro-magnet which, when being excited, acts on said displaceable pin,so as to hold same in the first position.
 4. An axial setting deviceaccording to claim 2, wherein at said circumference of said pressuredisc, the free end of said displaceable pin and the flanks of saidnotches form angles with the radial direction which are greater than theself-inhibition angle.
 5. An axial setting device according to claim 3,wherein at said circumference of said pressure disc, the free end ofsaid displaceable pin and the flanks of said notches form angles withthe radial direction which are greater than the self-inhibition angle.6. An axial setting device according to claims 1, wherein a pretensionpressure plate spring, acts axially on said axially displaceablepressure disc towards said axially fixed disc.
 7. An axial settingdevice according to claim 2, wherein a pretension pressure plate spring,acts axially on said axially displaceable pressure disc towards saidaxially fixed disc.
 8. An axial device according to claim 3, wherein apretension pressure plate spring, acts axially on said axiallydisplaceable pressure disc towards said axially fixed disc.
 9. An axialsetting device according to claim 4, wherein a pretension pressure platespring, acts axially on said axially displaceable pressure disc towardssaid axially fixed disc.
 10. An axial setting device according to claim5, wherein a pretension pressure plate spring, acts axially on saidaxially displaceable pressure disc towards said axially fixed disc. 11.An axial setting device according to claims 1, wherein said outercircumference of said setting disc is provided with toothing and thatthere is provided a setting motor on whose shaft there is positioned aworm which engages said toothing.
 12. An axial setting device accordingto claim 2, wherein said outer circumference of said setting disc isprovided with toothing and that there is provided a setting motor onwhose shaft there is positioned a worm which engages said toothing. 13.An axial setting device according to claim 3, wherein said outercircumference of said setting disc is provided with toothing and thatthere is provided a setting motor on whose shaft there is positioned aworm which engages said toothing.
 14. An axial setting device accordingto claim 4, wherein said outer circumference of said setting disc isprovided with toothing and that there is provided a setting motor onwhose shaft there is positioned a worm which engages said toothing. 15.An axial setting device according to claim 5, wherein said outercircumference of said setting disc is provided with toothing and thatthere is provided a setting motor on whose shaft there is positioned aworm which engages said toothing.
 16. An axial setting device accordingto claim 6, wherein said outer circumference of said setting disc isprovided with toothing and that there is provided a setting motor onwhose shaft there is positioned a worm which engages said toothing. 17.An axial setting device according to claim 11, wherein a worm drive isprovided consisting of said setting disc and said worm which isself-inhibiting.
 18. An axial setting device according to claim 12,wherein a worm drive is provided consisting of said setting disc andsaid worm which is self-inhibiting.
 19. An axial setting deviceaccording to claim 13, wherein a worm drive is provided consisting ofsaid setting disc and said worm which is self-inhibiting.
 20. An axialsetting device according to claim 14, wherein a worm drive is providedconsisting of said setting disc and said worm which is self-inhibiting.21. An axial setting device according to claim 15, wherein a worm driveis provided consisting of said setting disc and said worm which isself-inhibiting.
 22. An axial setting device according to claim 16,wherein a worm drive is provided consisting of said setting disc andsaid worm which is self-inhibiting.
 23. An axial setting deviceaccording to claim 2, wherein said outer circumference of the settingdisc is provided with spur gear toothing and there is provided a settingmotor on which shaft there is positioned a spur gear pinion forengagement with said spur gear toothing.
 24. An axial setting deviceaccording to claim 3, wherein said outer circumference of the settingdisc is provided with spur gear toothing and there is provided a settingmotor on which shaft there is positioned a spur gear pinion forengagement with said spur gear toothing.
 25. An axial setting deviceaccording to claim 4, wherein said outer circumference of the settingdisc is provided with spur gear toothing and there is provided a settingmotor on which shaft there is positioned a spur gear pinion forengagement with said spur gear toothing.
 26. An axial setting deviceaccording to claim 5, wherein said outer circumference of the settingdisc is provided with spur gear toothing and there is provided a settingmotor on which shaft there is positioned a spur gear pinion forengagement with said spur gear toothing.